My BPs almost never hiss, but my Borneo STP does all the time. I just give a gentle pat and prove I'm not a threat. After a second or two I can pick them up no problem. As long as you're gentle you'll be fine.

I would just assume this to be an isolated incident and not sweat it. If the behavior keeps up it will be worth trying to troubleshoot and determine why she's hissing. But unless it keeps up I wouldn't worry about it.